It's always crazy to me to see this kind of smug takes defending huge corporations as if they're your friends.
It's not all good or bad, there's a security issue with side loading, as well as shovelware on the play store. However, there is no world where I would argue that these justify limiting consumer grade hardware to walled gardens.
It's less about defending and more about being annoyed with all the over-confident, uninformed opinions people frequently post in reaction to any news article on the subject.
Funny, as someone that uses Android, sideloads apps, and is the "tech guy" for some older people, I went "yep, Google's own Play Store is full of shitty apps".
I recommend getting an Android phone (there are cheap Google Pixels out there) and try to sideload an app. Also browse the web a bit without an adblocker. I'd be surprised if by the end of the experiment you thought that sideloading is the reason their grandma's phone is full of crap.